Circuit for regulating the torque of ratio meters

Abstract

In order to maintain the torque of the ratio meter and the drive of amplifiers feeding it independently of the amplitudes of a sine signal voltage and a cosine signal voltage, a regulation is provided. The regulation makes use of two-quadrant voltage-controlled sources of current each of which is connected to a coil branch. Control voltage amplifiers, one connected in front of each source of current, are furthermore used. A sum-current resistor is provided to form the sum of the supply currents of two voltage-controlled sources of current. The supply currents represent the amounts of the sine signal voltage and cosine signal voltage which act on the voltage amplifiers. From the resistor for the formation of the sum of the supply currents a signal is derived which switches the amplification of the voltage amplifiers automatically in the direction of compensation.

I claim: 
     
       1. A circuit for regulating the torque of ratio meters, particularly of compass indicators, in which two-quadrant voltage-controlled sources of current are connected to respective coil branches voltage amplifiers and feed the two current sources with a sine signal voltage and cosine signal voltage, respectively, the regulating circuit comprising means for forming the sum of supply currents of the two voltage-controlled current sources; and   means for automatically altering amplification factors of said amplifiers as a function of said sum of the supply currents,   said sum forming means comprises a resistor inserted into a line carrying the sum of the supply currents; said circuit further comprising a comparator having an input connected to said resistor; and wherein said altering means comprises a controlled switch which is controllable by the output of the comparator to change the amplification factor of each of the two voltage amplifiers, and wherein   each voltage-controlled source is formed essentially of two operational amplifiers which are connected in tandem, said current sources serving as impedance transformers for the feeding of one of the two coil branches, and wherein one of said current sources is switched with a current which is proportional to the sine current voltage, a total of four operational amplifiers being formed as a quadruple operational amplifier on one chip, the resistor being connected in a common supply-current line of the quadruple operational amplifiers.   
     
     
       2. The circuit according to claim 1 wherein each voltage-controlled current source is formed of an integrated circuit (IC), and wherein current supply for both integrated circuits are conducted via said resistor.   
     
     
       3. The circuit according to claim 1 wherein said resistor is coupled by an integrating resistor-capacitor circuit to an input of said comparator.   
     
     
       4. The circuit according to claim 1 wherein said controlled switch is a controlled semiconductor switch in a resistor negative-feedback branch of each of said voltage amplifiers.   
     
     
       5. A circuit for regulating the torque of ratio meters, particularly of compass indicators, in which two-quadrant voltage-controlled sources of current are connected to respective coil branches voltage amplifiers and feed the two current sources with a sine signal voltage and cosine signal voltage, respectively, the regulating circuit comprising means for forming the sum of supply currents of the two voltage-controlled current sources; and   means for automatically altering amplification factors of said amplifiers as a function of said sum of the supply currents, and wherein   each voltage-controlled source is formed essentially of two operational amplifiers which are connected in tandem, said current sources serving as impedance transformers for the feeding of one of two coil branches, and wherein one of said current sources is switched with a current which is proportional to the sine current voltage, a total of four operational amplifiers being formed as a quadruple operational amplifier on one chip, a resistor being connected in a common supply-current line of the quadruple operational amplifiers.   
     
     
       6. The circuit according to claim 5 wherein each voltage-controlled current source is formed of an integrated circuit (IC), and wherein current supply for both integrated circuits are conducted via said resistor.